1. Field of the Invention
The present invention is directed to a hearing aid device of the type which can be worn in the ear, or at the ear with an otoplastic worn in the ear, as well as to a method for operating such a hearing aid. In particular, the invention relates to a method and hearing aid allowing ventilation of the volume of the auditory canal which is closed by the hearing aid or by the otoplastic.
2. Description of the Prior Art
In the practical application of hearing aid devices, the auditory canal is closed in many instance by an otoplastic or by a hearing aid device seated in the auditory canal. In order to nonetheless assure a certain aeration of the enclosed auditory canal volume and in order to be able to counter the acoustic effects associated with a closed auditory canal, a small aeration channel, also referred to as ventilation opening or merely xe2x80x9cventxe2x80x9d, is integrated into the otoplastic or into the hearing aid device worn in the ear.
Limits, however, exist as to the size of this aeration channel from the acoustic side since too many sound components would exit the residual volume of the auditory canal through a large aeration channel and could thus proceed to the microphone of the hearing aid device. The result would be feedback-caused oscillations (feedback). Thus only an aeration channel having a comparatively small cross-section can usually be employed.
Heretofore, it has been up to the hearing aid acoustician to integrate a vent into a hearing aid device that is matched to the hearing impairment and further individual conditions of a hearing aid user. For insuring higher acoustic stability comparatively small ventilation openings have generally been used, resulting in an inadequate aeration of the enclosed auditory canal volume.
German OS 199 42 707 discloses a hearing aid device to be worn in the ear or a hearing aid device with otoplastic to be worn in the ear wherein an aeration channel is present. Additionally, means for throttling or closing the aeration channel are present in this known hearing aid device. The setting of this means ensues with corresponding operating elements for a hearing aid device worn at the ear or by means of the signal processing unit of the hearing aid device or by programming of the hearing aid device.
A disadvantage of such known hearing aid devices to be worn in the ear or hearing aid devices with otoplastic to be worn in the ear is the inadequate aeration of the auditory canal given the usually small ventilation openings. Poor wearing comfort or even inflammation in the auditory canal thus frequently arise.
An object of the invention to improve the aeration of the auditory canal given for hearing aid device to be worn in the ear or a hearing aid device with otoplastic to be worn in the ear.
The above object is achieved in a hearing aid device to be worn in the ear or a hearing aid device with otoplastic to be worn in the ear, having at least one input transducer for the pickup of an acoustic or electromagnetic input signal and conversion into an electrical signal, a signal processing unit for processing and amplification of the electrical signal and an earphone for converting the electrical signal into an acoustic signal, at least one first aeration channel and at least one second aeration channel for ventilating the auditory canal volume enclosed by the hearing aid device or the otoplastic. The aeration channels have respective structures allocated to them for promoting a flow direction through the aeration channel, for promoting the flow of air out of the enclosed auditory canal volume in the first aeration channel and for promoting the flow of air into the enclosed auditory canal volume in the second aeration channel.
Further, this object is achieved in a method for the operation of a hearing aid device to be worn in the ear or a hearing aid device with otoplastic to be worn in the ear, wherein a drive signal having a signal frequency in an inaudible frequency range is generated and superimposed on the electrical signal and output via the earphone into the auditory canal for the active ventilation of the auditory canal.
The hearing aid device of the invention is, for example, a hearing aid worn in the ear (ITE), a hearing aid worn behind the ear (BTE) or on the body that is connected to an otoplastic worn in the ear, a communication device worn in the ear, a part of a communication system worn in the ear, for example a headset worn in the ear for connection to a mobile telephone, etc. A part that closes the auditory canal is arranged in the auditory canal in all of these devices. The natural ventilation of the auditory canal is thus largely suppressed.
The hearing aid device of the invention has an input transducer, for example a microphone, an auditory coil or an antenna that picks up the input signal and converts it into an electrical signal. The electrical signal is further-processed in a signal processing unit and is usually amplified with a gain that is dependent on the frequency. An earphone converts the electrical signal processed in this way into an acoustic signal that is emitted into the auditory canal of a user.
In a hearing aid device worn in the ear, the earphone is arranged in the hearing aid device, and thus in the auditory canal. The situation is different in a hearing aid device with an otoplastic. Here, the earphone can be arranged in the otoplastic or alternatively can be arranged outside the auditory canal, for example within a hearing aid device worn behind the ear. The sound conduction from the earphone into the auditory canal ensues via a sound conduit connected to the otoplastic.
As a result of the (at least two) aeration channels in combination with flow resistances arranged in the aeration channels that promote a flow from the enclosed auditory canal volume toward the outside in at least one aeration channel and promote a flow into the enclosed auditory volume in at least one other aeration channel, a flow through the enclosed auditory canal volume results overall, so that an air exchange ensues therein. This improves the wearing comfort of the hearing aid device and contributes to avoiding diseases caused by a poor ventilation of the auditory canal.
The flow is driven, for example, by movements and volume changes of the auditory canal associated therewith of the kind produced when talking or chewing.
In a preferred version of the invention, a further signalxe2x80x94the drive signalxe2x80x94is emitted as a component of the acoustic output from the earphone in addition to the processed signal, this further signal being in an inaudible frequency range and therefore not being perceived by the user. By interaction with the flow resistances in the aeration channels with the earphone, a membrane pump thereby is created that causes to an air flow through the enclosed auditory canal volume, and thus effects an active ventilation of the enclosed auditory canal volume.
A signal generator, for example a sine generator, can be used to generate the drive signal. The ventilation effect produced by the earphone thereby improves with increasing amplitude of the drive signal, for which reason an optimally high amplitude is preferred. A movement of the earphone membrane, preferably a low-frequency movement thereof, that is not produced by the payload signal arises in this way, this seeing to a uniform flow of air into and out of the earphone. During operation of the hearing aid device, however, care must be exercised to be sure that the earphone membrane does not reach its full modulation due to the superimposition of the payload signal with the drive signal, since audible artifacts thus would be generated.
A special structuring of the aeration channels can achieve a privileged pass direction of the aeration channels. For example, an aeration channel can gradually and continuously narrow in one pass direction and in turn abruptly expand to the original circumference. The same measure is undertaken in the second aeration channelxe2x80x94preferably arranged parallel to the first; however the gradual and continuous constriction ensues in the other direction. Given, for example, an elevated pressure in the enclosed auditory canal volume compared to the ambient pressure, the channel that narrows steadily and gradually toward the outside offers lower flow resistance than the aeration channel having an abrupt constriction facing toward the enclosed volume. On average, an air flow toward the outside thus ensues through the first aeration channel, and an air flow toward the inside ensues through the second aeration channel. Overall, an air flow thus is produced through the enclosed auditory canal volume, and thus an air exchange. The functioning thus mimics that of a membrane pump.
Usually no specific earphones are required for the operation of a hearing aid device of the invention. For earphones that are usually utilized, a pressure compensation between the two separate air volumes separated by the membrane is not provided for the dynamic operating condition. Micro-bores may be arranged laterally next to the membrane for static pressure compensation, but these have no influence on the dynamic operation.
In order to promote the flow in one direction through an aeration channel, valves or flaps can be arranged at an input of the aeration channel or within the aeration channel according to one version of the invention. Although valves or flaps require a higher mechanical outlay for manufacture, they nonetheless guarantee that the flow through the aeration channel ensues nearly exclusively in one direction.
Automatically actuatable valves or flaps are even more mechanically complicated but are even more efficient. These valve or flaps have electrical or magnetic miniature drives allocated to them that are preferably driven directly with the drive signal for the earphone. The valves or flaps are thus opened or closed with the clock of the drive signal, with the valves or flaps in the one aeration channel being opened while the valves or flaps in the other aeration channel close.
Preferably, the miniature drivesxe2x80x94but also the valves or flapsxe2x80x94are at least partly manufactured in micro-structure technology. Such methods allow an economical manufacture of high unit numbers of nearly arbitrarily small miniature actuators.
The drive signal for driving the earphone in a hearing aid device of the invention preferably is generated with a signal generator. This, for example, can be a sine generator, however, other drive signals also come into consideration, for instance square-wave signals. In order to be able to adapt the aeration to the individual needs of a user, the amplitude and/or frequency of the drive signal are advantageously adjustable. For example, the setting can ensue by programming the hearing aid device. This allows the air volume to be exchanged per time unit to be approximately set.
In an advantageous embodiment of the invention the setting of the drive signal ensues dependent on characteristics of the input signal or the electrical signal. The drive signal should have a relatively high amplitude for achieving a good ventilation effect. It is superimposed on the processed signal and is emitted as an output via the earphone. Particularly given a processed signal with a comparatively high amplitude, there is thus the risk of an overdrive of the earphone, which would generate audible artifacts. By acquiring the signal level of the input signal or the amplitude of the electrical signal, overdrive can be prevented by reducing the amplitude of the drive signal given an electrical signal with a high amplitude. As warranted, the drive signal can even be completely turned off given an electrical signal with an especially high amplitude. In a very quiet acoustic environment, further, the frequency and/or the amplitude of the drive signal can be reduced in order to reduce or avoid flow noises potentially produced by the active aeration.
The setting of the drive signal dependent on the auditory program that has been set is also possible. For example, the ventilation activity is throttled in case of an auditory program for a quiet environment.
In a further embodiment of the invention, a sensor is provided for acquiring at least one characteristic of the auditory canal volume enclosed by the hearing aid device worn in the ear or the otoplastic worn in the ear. For example, the size of the enclosed auditory canal volume or the relative humidity in the enclosed auditory canal volume can be measured with this sensor. In response thereto, the ventilation activity is adapted to the characteristic measured in this way. Given a relatively high relative humidity in the auditory canal, for example, the ventilation activity can be increased by increasing the frequency of the drive signal.